title: In planta distribution of 'Candidatus Liberibacter asiaticus' as revealed by polymerase chain reaction (PCR) and real-time PCR.
abstract: Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide, and is caused by a phloem-limited fastidious prokaryotic alpha-proteobacterium that is yet to be cultured. In this study, a combination of traditional polymerase chain reaction (PCR) and real-time PCR targeting the putative DNA polymerase and 16S rDNA sequence of 'Candidatus Liberibacter asiaticus,' respectively, were used to examine the distribution and movement of the HLB pathogen in the infected citrus tree. We found that 'Ca. Liberibacter asiaticus' was distributed in bark tissue, leaf midrib, roots, and different floral and fruit parts, but not in endosperm and embryo, of infected citrus trees. Quantification analysis of the HLB bacterium indicated that it was distributed unevenly in planta and ranged from 14 to 137,031 cells/mug of total DNA in different tissues. A relatively high concentration of 'Ca. Liberibacter asiaticus' was observed in fruit peduncles. Our data from greenhouse-infected plants also indicated that 'Ca. Liberibacter asiaticus' was transmitted systemically from infection site to different parts of the plant. Understanding the distribution and movement of the HLB bacterium inside an individual citrus tree is critical for discerning its virulence mechanism and to develop management strategies for HLB.
authors.affiliation: Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, USA.
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Tatineni
authors.forename: Uma Shankar
authors.initials: US
authors.lastname: Sagaram
authors.forename: Siddarame
authors.initials: S
authors.lastname: Gowda
authors.forename: Cecile J
authors.initials: CJ
authors.lastname: Robertson
authors.forename: William O
authors.initials: WO
authors.lastname: Dawson
authors.forename: Toru
authors.initials: T
authors.lastname: Iwanami
authors.forename: Nian
authors.initials: N
authors.lastname: Wang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D002957:Citrus / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012230:Rhizobiaceae / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D004259:DNA-Directed DNA Polymerase